Safety attachment for presses.



J. PRACHAR.

SAFETY ATTACHMENT FOR PHESSES.

APPLICATION FILED SEPT. I3, 1916.

MWWW 4i SHEETS-SHEET I.

Patented Dec. 4,,1917.

J. PRACHAR.

SAFETY ATTACHMENT FOR PRESSES.

1 APPLICATION FILED SEPT. l3. I9l6- 4 SHEETS- SHEET 2'.

"U v o N Q O K v I Patefited 10%. 4,1917.

1. PRACHAR. SAFETY ATTACHMENT FOR PRESSES.

APPLICATION FILED SEPT. 13, I916.

Patented Dec. 4,1917.

4 SHEETS-SHEET 3.

J. PRACHAR.

SAFETY ATTACHMENT FOR PRESSES.

APPLICATION FILED SEPT. 13. 1916.

Patented Dec. 4, 1917.

4 SHEETS-SHEET 4- JGHN PRACI-IAR, 0F CLEVELAND, OHXO, ASSIGNOR OF ONE-THIRD TO CHARLES 1?. KREUZER AND ONE-THIRD T0 FRED G. JULYAN, BOTH 0F CLEVELAND, OHIO.

SAFETY ATTACHMENT FOR PRESSES.

meager.

Specification of Letters Patent.

Patented Dec. 4, 119172.

Application filed September 13, 1916. Serial No. 119,807.

To all whom it may concern:

Be it known that T. JOHN PRACHAR, a citizen of the United States, residing at Eleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Safety Attachments for Presses, of which the following is a full, clear, and exact description.

This invention relates to safety devices for presses, particularly punch presses and has for its chief object to provide in combination with a press a safety device or guard which stops or prevents the descent of the plunger carrying the movable punch or die if the hand of the operator, or in fact, any obstruction is in, or approximately in the path of movement of the plunger. A further object is to provide a safety guard which can be applied to standard punch presses and which is adapted to be utilized in connection, with the clutch mechanism provided thereon without altering the construction of the press or of the clutch mechanism.

The safety mechanism which is in the form of an attachment for standard or comm-ercial punch presses includes a movable safety guard which is preferably pivoted to swing upwardly and downwardly, and in its movement encompasses, or substantially surrounds the lower part of the plunger adja cent the bed or lower die. Ihis guard which is elevated by a cam on the power driven or rotating part of the press, permits the plum ger of the press to descend only if the guard has been allowed to swing downward to its lower limit of movement, but if the movement of the guard is arrested by any obstruction, such as the hand of the operator, the shaft of the press operating the plunger is immediately unclutched, preventing the descent of the plunger. After the obstruction is removed the safety device continues its downward movement, or is manually moved downward bv the operator, in which event the clutch elements are again enga ed, permitting the plunger to make its complete downward and thence upward stroke.

The invention may be further briefly sum? marized as consisting in certain novel details of construction and combinations and arrangements of parts which will be described in the specification and set forth in the appended claims.

In the accompanying sheets of drawings, wherein I have shown some slightly different forms of my inventioml igure 1 is a side view of a punch press equipped with my invention, the plunger and safety device being elevated; Fig. 2 is a view of the main portion of the press illustrating the manner in which the descent of the plunger is arrested by an obstruction such as the hand of the operator in the path ofmovement of the guard or safety device, parts being broken away; Fig. 3 is a similar view showing the guard in its lowermost position and the plunger at the end of its downward stroke; Fig. 4 is a front view of the press and safety mechanism; Fig. 5 is an enlarged view, partly in section, and with parts broken away showing particularly the clutch controlling portions of the safety mechanism; Fig. 6 illustrates detached, the clutch pin and one of the pin shifting shoes; Fig. 7 is a side view of the upper portion of a press showing a different form of clutch mechanism, and also a modification in the construction of the safety mechanism; 8 is a front view of the same and Fig 9 is an enlarged view with. portions broken away, showing particularly the clutch mechanism of the press shown in F igs 7 and 8.

Referring first to Figs. 1 to 6, 10 represents the frame of the press which has a bed or die support 11 on which is mounted the lower die 12. An upper die 13 is carried by a vertically movable plunger let, connected in the usual manner at its upper end to a crank of an operating shaft 15, mounted in suitable bearings in the upper part of the frame. The shaft is adapted to be driven and to be clutched and unclutched from a power applying device. in this case, in the form of a fly-wheel pulley 16. This fly-wheel pulley is provided on its inner face with one or more clutch sockets 17 into which is adapted to be inserted the endof an endwise movable clutch pin or jaw 18, (see particularly Fig. 5) which pin is carried by a collar 19 fixed to the shaft 15. This pin or jaw, which. isurged inwardly toward the pulley by a spring 20, is nor mally controlled by mechanism including a pivoted pedal 21, (see Fig. 1) connected by in the clutch pin or jaw 18. Both the shoe and the slot 27 of the clutch pin are provided with tapered portions (see Fig. 6) which will cause a camming action on the pin 18 and shift the latter out of the socket or opening in the fly-wheel so as to unclutch the shaft and fly-wheel, this action. taking place when the shoe is permitted to move inwardly toward the slot 27 in the clutch pin. A spring 28 which surrounds the plunger 24 tends at all times to move the shoe 26 and plunger 24 inwardly to unclutching position, and also to elevate thepedal 21.

The safety guard per seis in the form of a U-shaped member 30 which extends around the sides and across the front of the dies, and is designed to swing from its upper position, shown in Fig. 1, in which event its front portion is some distance above the lower die, to a lower position shown in Fig. 3, in which event a projection 31 on the front part of the U-shaped member is substantially down on the bed or part carrying the lower die, as shown in Fig. 3. The ends of this U-shaped member are secured to a rocking shaft 32, which extends across the press at the rear of the plunger. (See particularly Fig. 4). This transverse shaft 32, which is mounted in suitable hearings on the frame of the press, has fixed to it a lever 33, to the rear end of which is connected a spring 34, which tends to swing the lever and hence rock the shaft 32 so as to lowerthe safety device or to move it to the position shown in Fig. 1. The front end of this lever 33 is pivotally connected to an upright rod 35, which near upper end passes through a suitable guide 36. The upper portion ofthis arm or rod 35 is curved forwardly and downwardly, and at its upper free end is provided with the roller 37, designed to be engaged by a cam lug 38, carried by the collar 19, which as before stated, rotates with the operating shaft.

In order that the safety device may control'the movement of the plunger, I provide adjacent to the regular clutch shoe 26, a second clutch shoe 39 which in all respects is similar to the clutch shoe 26. This sec ond clutch shoe 39 is carried by a plunger 40,'spring-pressed inwardly by a spring 41, and mounted in bearings of a casting 42 which is secured to the upper part of the frame .of the press (see particularly Fig. 5).

The outer end of the plunger has a connection with one arm of a bell crank lever 43 which is pivoted at 44 on the casting 42. The other arm of this bell-crank lever is pivoted. at45 to the arm or rod 35, extending upwardly from the lever 33, which as before explained, rocks the safety member or guard. The construction is such that when the rod moves downward substantially until the roller rests on the periphery of the collar 19, then, and only in that event, is the shoe at the end of the plunger 40 retracted sufiiciently from the clutch pin or jaw 18 to permit the parts of the clutch to remain in clutching engagement; but when it is elevated, or at all above its lowermost position, the inner portion of the shoe will engage in the slot 27 of the clutch pin or jaw and shift the latter outwardly so as to unclutch the shaft. This takes place when the downward movement of the U-shaped safety frame or guard is stopped before the guard reaches its lowermost position, as indicated in Fig. 2.

The operation of the safety device and punch press is as follows: \Vhen the shaft of the press is unclutchcd from the fly-wheel pulley after each cycle of operation, the

parts are in the position shown in Fig. l,v

that is to say, the plunger of the press is elevated and the guard 30 is swung upward to its uppermost position, the guard having been elevated by the cam 38 by its engage-- ment with the roller 3'7, the latter being on the tip of the cam and about to drop off the same when the press comes to rest. When the operator depresses the pedal 21, the shoe 26 is retracted, permitting the clutch pin to snap into the socket of the rotating fly-wheel. pulley. This clutches the pulley to the shaft 15 and starts rotation of the latter, causing the roller 37 to ride off the cam 38 and permitting the arm or rod 35 to drop and the guard 30 to swing downward. If there is no obstruction in the path of movement of the guard the arm 35 drops its full distance, causing the withdrawal of the shoe 39 out of the path of movement of the clutch pin, but if the guard is not permitted to swing downward its full distance, the shoe 39 is not retracted or withdrawn entirely out of the path of the clutch pin, with the result that the shaft is immediately unclutched from the rotating pulley by reason of the fact that the clutch pin is cammed by the shoe 39 out of the clutch socket of the pulley. The stopping of the press in the event that there is an obstruction in the path of the swinging guard 30 takes place immediately after the shaft is clutched to the pulley by the withdrawal of the shoe 26, and after only a very few degrees of movement of the shaft 15, and before the main plunger 14 has any more than started on its downward movement, the clutch shoes 26 and 39 are so positioned with respect to each other, and the cam 38 is so positioned with respect to the clutch pin that the latter passes from the clutch shoe 26 to the clutch shoe 39 very quickly so that almost instantly after the withdrawal of the shoe 26 by the operation of the pedal the roller 37 rides 0H the cam 38 and the arm or rod 39'either drops its full distance, in which event the plunger of the press makes its downward and then upward stroke, or if the guard strikes an obstruction, the arm 35 drops only part way downward, in which event the press is instantly stopped. To cause a continued operation of the press, after it has stopped in the manner just explained, the operator will remove his hand or'other obstruction from beneath the guard whereupon the guard will drop to its lowermost position, causing the shoe 39 to be further withdrawn so as to permit the clutch pin again to snap backinto clutching position.

In Figs. 7 to 9, I have shown a modification in the form of the clutch and in the dis position of the .clutch shoes and mechanism for operating the same. In this form of the machine, the clutch includes a clutch collar 50, which is slidable on'the shaft 15, but rotates with the latter, the collar being connected with the shaft by plurality of keys which permit the collar to be shifted lengthwise of the shaft. The collar is provided on one side with clutch jaws which engage somewhat similar jaws on the adjacent face of the hub of the fly-wheel pulley, which is here designated 51. This clutch collar 50 is provided on its periphery with a lug 52, having a tapered or camming face which is designed to be engaged successively by the roller 53 on a pin or plunger 54L connected to the pedal and by a roller 55 on the end of a pin or plunger 56, which is connected to the safety guard. The pin or plunger 54: carrying the roller 53 is in this case vertically arranged and is mounted for endwise move ment in bearing lugs of a casting 57 secured to the frame of the press. At the upper end of the pin or plunger is a weight 58, which tends to move the pin 54 and roller 53 downward to normal position. The pin 54, roller 53 and weight 58 are elevated so as to move the roller beyond the cam lug 52 and-to permit the clutch collar 50 to be moved by springs 50 into clutching engagement with the fiy-wheel pulley by means of a lever 59, which is connected by rods 60 and 61 to a pedal, not shown but similar in all respects to the pedal 21 to the first described construction. The other roller 55, which is also adapted to engage cam lug 52 is as above stated carried by a pin 56 which is mounted for endwise movement in bearing lugs of a casting 62 which is secured to the frame of the press. The outer end of this pin 56 is connected by a pin and slot connection to an arm 63 of a pivoted device'having two additional arms 64 and 65. At the end of arm 64- is a roller 66 adapted to be engaged by a cam 67 likewise on the periphery of the clutch collar 50. The third arm is connected by a rod 68 to a crank on the end of permitting the clutch collar 50 to slip in.

clutching engagement with the fly-wheel pulley 51. Almost immediately the roller 66 rides off the periphery of the cam 67 and when this takes place the roller swingsinwardly to the periphery of the clutch collar and the guard swings downwardly, being pulled downward by aspring 71, and if there is no obstruction in the path of the guard, the roller 55 coincident with the downward movement of the guard and the inward movement of the roller 66, shifted outwardly beyond the path of movement of the cam 52, and the downward and thence upward stroke of the press plunger takes place. On the other hand, if the movement of the guard 70 is arrested before the guard completes its downward swinging movement, by striking the hand of the operator or any other 0bstruction, roller 55 does not move outwardly far enough to escape the oncoming cam 52, in which event the roller is engaged by the cam 52, immediately unclutching the shaft 15 from the fly-wheel pulley. WVhen the obstruction is removed, the guard continues its downward movement, the roller is moved outwardly beyond the cam 52, the clutch collar again moves into locking engagement with the fly-wheel pulley and the plunger makesits downward and thence upward strokes, after which itwill be stopped by engagement of the cam 52 with the roller 53. Just at the end of the upward movement of the plunger the cam 67 engages the roller 66, causing the guard to be elevated and moving the roller 55 inwardly, and when the press comes to rest the roller 66 is near the point of the cam 67 so as to ride off the same as soon as the press is again started.

It is to be noted that the safety mechanism including the guard and the clutch con trolling parts employed therewith is in both instances applied to a press without altering the construction of the latter and without requiring a special construction of any part of the press to admit of the application of the safety mechanism.

It will be obvious from the two forms of apparatus shown that the invention is susceptible of modification as to the form and arrangement of parts and that the safety mechanism may be applied to presses provided with different types of clutch mechanisms. I therefore do not desire to be confined to any of the precise details shown or to any particular form or arrangement of parts but aim in my claims to cover all modifications which do not involve a departure from the spirit and scope of my invention.

Having described my invention, I claim:

1. In combination in a press a plunger, a shaft for operating the same, a power actuated wheel for rotating the shaft, a clutch for clutching and unclutching the shaft and wheel and including a movable clutch member, a safety attachment including a movable guard having a definite range ofmove ment adjacent the plunger, and adapted to precede the effective working movement of the latter, two clutch controlling elements, each adapted to shift said movable clutch member to unclutching position, means under the control of the operator for shifting one of said clutch controlling elements thereby causing the shaft to be clutched to the wheel, means connecting said guard to the other clutch controlling element, and means for causing the guard and last named clutch controlling element to be shifted immediately after the clutching of the shaft and wheel.

2; In combination in a pressa plunger, a shaft for operating the plunger, a power actuated Wheel for driving the shaft, a reciprocating guard. adapted to be swung upwardly and downwardly adjacent to the plunger and to move downwardly prior to the downward movement of the plunger, a clutch for connecting the shaft and power actuated wheel including a clutch element carried by the shaft and movable to and from clutching position, a clutch controlling member adapted to be shifted by the operator to cause the clutching of the shaft and wheel, means rotatable with the shaft for elevating the guard and for holding same elevated when the shaft and wheel are unclutched by said clutch controlling element, and a second clutch controlling element connected to the guard and arranged adjacent the first named clutch controlling element, said second clutch controlling element serving to cause the unclutching of the shaft after it has been clutched thereto as a result of the movement of the first named clutch controlling element when the regular or definite downward movement of the guard has been obstructed.

Copies of this patent may be obtained for 3. In combination in a press a bed, a plunger movable toward and from the same, a shaft for operating the plunger, a power actuated wheel for rotating the shaft, a clutch member movable lengthwise of the shaft, a guard mounted to swing adjacent the plunger and to move toward the bed prior to the corresponding movement of the plunger, means rotatable with the shaft for raising the guard and for releasing the same so that it may move toward the bed, and two clutch controlling elements, one adapted to be shifted by the operator so as to release said movable clutch member and permit the shaft to be clutched to the wheel and the guard to be released, and the second connected to the guard so as to move therewith and serving to unclutch the shaft unless the guard moves its full distance toward the bed.

i. In combination in a press a reciprocating plunger and bed, a power actuated wheel for driving the shaft, a clutch for connecting the shaft and wheel, and including an annular member rotatable with the shaft adapted to be clutched to the wheel, a guard adapted to move upwardly and downwardly adjacent the plunger, and to move downwardly just prior to the downward movement of the plunger, two endwise movable clutch controlling elements adjacent each other and adjacent said annular member, means connected to one of said clutch elements whereby it may be shifted by the operator so as to cause the shaft to be rotated by the wheel, the second clutch controlling element being connected to the guard so as to move coincidently therewith, a cam on said annular member, a cam engaging member connected to the second clutch controlling element and to said guard and adapted to be engaged by said cam so as to elevate the guard and move said clutch controlling element outwardly with respect to said annular member, whereby, after the shaft is clutched to the wheel and after said cam passes beyond the cam engaging member said guard is lowered and the clutch controlling element connected thereto is moved inwardly.

In testimony whereof, I hereunto ailix my signature.

JOHN PRACHAR.

five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

